During the first week of December the IFS completed an electrofishing survey on Arthurs Lake.  This survey (which is now completed annually) was first done in 2022, when 200 otoliths (ear bones) were collected from a sample of 200 brown trout for the purpose of ageing fish.

This year, over a two day period, the IFS captured 170 brown trout. They were weighed and measured before being released back into the lake. Of these, 20 were male, 37 female, with 102 unable to be determined as either male or female (immature fish).

The proportion of undetermined or immature fish in this years survey was 66 percent. This compares to 30 per cent for 2023 and 51 per cent for 2022.

There has been a reduction in the average weight of fish across the last three surveys - 353 g in 2022, 334 g in 2023 and 286 g in 2024.

The lower average size of trout at Arthurs Lake is directly attributed to the high level of recruitment from the spawnings between 2020 to 2023 and coincides with three consecutive La Niña event years.

A full report on the 2024 Arthurs Lake trout survey will be published on the IFS website in the new year.

All fishery assessment reports for the past year can be viewed at Fisheries Performance Assessment Reports.